This invention relates in general to delay memory devices and, in particular, to an addressable digital delay memory device for use in an addressable encoder system. The invention relates especially to an addressable delay memory device in which data words may be delayed for varying periods and specified data words may be presented at the device output on the command of a master controller.
In aerospace testing and communications, one function of a digital telemetry system is to provide delayed transmission of some or all of the data in order to provide redundant radio links and to collect data from periods during which radio reception is impossible. This is accomplished by storing the data in a semiconductor memory and sending the data out some time later. In the typical system, the delay memory receives the data, stores the data for a defined period of time and then presents the data at an output for transmission to an external receiver on a first in - first out basis.
Although the first in-first out delay memory devices are satisfactory for many applications, increasingly complex aerospace systems and increasing data monitoring requirements have created a need for more flexibility in the delay memory device. It is now desirable to employ a delay memory in which the data words may be delayed for varying periods of time and specific data words selected for output as required by an external master controller.